Abstract

Conventional optical coherence tomography is based on A-scans, i.e., the fast scan direction is the z-direction. While this technique has been successfully demonstrated for two-dimensional cross sectional imaging of various tissues, it is rather slow if three-dimensional information is to be obtained. We report on a new technique that combines the transverse scanning approach of a confocal scanning laser ophthalmoscope with the depth sectioning capability of OCT. A stable high-frequency carrier is generated by use of an acousto optic modulator, and high frame rate is obtained by using a resonant scanning mirror for the priority scan (x-direction). Our prototype instrument records 64 transverse images consisting of 256×128 pixels in 1.2 seconds, thus providing the fastest retinal 3D OCT scanning system reported so far. We demonstrate the capabilities of our system by measuring and imaging the fovea and the optic nerve head region of healthy human volunteers in vivo.

(1.16 MB) Frame no. 10 of movie showing the recording sequence of a 3D OCT data set in the fovea of a healthy volunteer. Image size: 10°×10°. Depth step size between individual movie frames: 16 µm. 45 transversal frames out of a total of 64 are shown (the first frames corresponding to positions entirely in the vitreous are omitted).

(717 kB) Frame no. 33 of movie showing software derived B-scans through the fovea of a healthy volunteer. Same data set as in fig. 2. The upper part of the figure shows an SLO-like projection image (10°(x)×10°(y)) of the foveal area, the lower part shows the B-scan corresponding to the actual movie frame (10°(y)×1.05 mm(z)). The red indicator line at the right hand side of the projection image indicates the y-position corresponding to the actual movie frame.

(772 kB) Frame no. 35 of movie showing software derived B-scans through the optic nerve head of a healthy volunteer. The left part of the figure shows an SLO-like projection image (10°(x)×10°(y)) of the nerve head area, the right part shows the B-scan corresponding to the actual movie frame (10°(y)×1.05 mm(z)). The red indicator line at the bottom of the projection image indicates the x-position corresponding to the actual movie frame.